If the first number behind the decimal point is lower than five, you leave the digits in front of the decimal the same. If it is equal to or above five, then the number in front of the decimal is rounded up. In this case it would stay the same, so your answer would be 585.
To know if we should round 5 up or down, we look for the number to the right of the 5. If its 5 or higher, we round up. If its 4 or less we round down.
3 is the number, and its 4 or less so we round down. 585.30 becomes
